The present invention relates to a drive train for a motor vehicle, having an internal combustion engine and a hydraulically shiftable transmission unit, the input of which can be connected via a clutch arrangement to a crankshaft of the internal combustion engine and the output of which can be connected to driven wheels of the motor vehicle, the crankshaft being connected, furthermore, to a pump shaft which drives a pump arrangement for a hydraulic arrangement, by means of which the transmission unit is shifted and/or lubricated, and the pump shaft being connected, furthermore, to an electric machine.
A drive train of this general type is known from document DE 43 42 233 B4.
This document discloses an oil-pump drive device having an electric motor which can be connected via a first one-way clutch to a drive shaft of an oil pump, and having a machine which can be connected via a second one-way clutch to the drive shaft of the oil pump, the type of connection depending on the rotational speed of the output shaft of the machine.
Further arrangements for driving transmission oil pumps are known from documents DE 103 29 215 A1 and DE 102 51 042 A1.
In the drive train which is mentioned in the introduction, the electric machine can serve, for example, to drive the pump arrangement for the hydraulic arrangement when the internal combustion engine is not running, for example during start/stop operation of the motor vehicle. In this case, it is possible, for example, to supply the transmission unit with lubricating oil via the pump arrangement which is driven in this way.
The oil-pump drive device which is disclosed in document DE 43 42 233 B4 has a relatively complex construction, since the electric machine is to be connected to the pump shaft from outside a housing of the transmission unit.